Page authority represents the relevance of content, e.g. information and links, within pages to one another, and domain authority represents the reliability of the domain and relevance of the domain to a topic, for example a search keyword. Conventionally, authority rankings for pages and domains are based on the link structure of a network (e.g., the Internet). For example, authority values for a page might be determined based on the quantity and quality of other pages and domains that include links to that page. In many cases, however, these authority measures do not accurately reflect users' perceptions.